Observation of Associated Near-Side and Away-Side Long-Range Correlations in ���sNN=5.02 TeV Proton-Lead Collisions with the ATLAS Detector

Two-particle correlations in relative azimuthal angle (????????????) and pseudorapidity (????????????) are measured in ?????????sNN=5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 ??????b-1 of data as a function of transverse momentum (pT) and the transverse energy (??????ETPb) summed over 3.1<??????<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|????????????|<5) "near-side" (?????????????????????0) correlation that grows rapidly with increasing ??????ETPb. A long-range "away-side" (???????????????????????????) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ??????ETPb, is found to match the near-side correlation in magnitude, shape (in ???????????? and ????????????) and ??????ETPb dependence. The resultant ???????????? correlation is approximately symmetric about ??????/2, and is consistent with a dominant cos2???????????? modulation for all ??????ETPb ranges and particle pT. ?????? 2013 CERN.